712 University of California Publications in Botany [Vol. 8 



7. Cryptostomata conspicuous 8 



7. Cryptostomata minute or none 9 



8. Branches and branchlets muricate 6. S. horridum (p. 715) 



8. Branches and branchlets smooth 7. S. Marchantae (p. 715) 



9. Leaves lanceolate, acuminate, spinulose-dentate 8. S. Liebmanni (p. 716) 



9. Leaves more or less asymmetrical 10 



10. Primary branches long and very slender, branchlets sparse 



10. S. insulare (p. 717) 



10. Primary branches more robust, branchlets abundant 



9. S. Agardhianum (p. 716) 



11. Cryptostomata absent 12 



11. Cryptostomata sparse or abundant 13 



12. Leaves blunt 11. S. Brandegeei (p. 718) 



12. Leaves acute 16. S. herporhizum (p. 720) 



13. Fronds muricate 13. S. polyacanthum f. americanum (p. 718) 



13. Fronds smooth 14 



14. Leaves narrowly lanceolate to filiform, ecostate, vesicles ellipsoidal.... 



14. S. Johnstonii (p. 719) 



14. Leaves lanceolate, with percurrent midrib, vesicles subspherical to 



ovate 17. S. paniculatum (p. 721) 



14. Leaves lanceolate, with percurrent midrib, vesicles spherical 15 



15. Cryptostomata sparse, inconspicuous, receptacles acuminate 



12. S. sinicola (p. 718) 



15. Cryptostomata abundant, conspicuous, receptacles blunt 



15. S. cylindrocarpum (p. 720) 



1. Sargassum Palmeri Grunow 



Plate 41, fig. 56, and plate 94 



Frond arising: from a solid, rugose, more or less disk-shaped hold- 

 fast, 4.5-7 dm. high ; stipe terete, verrucose, up to 18 cm. long, bearing 

 2-5 terete or slightly angled, alternate branches at its summit disin- 

 tegrating after fruiting ; the primary branches giving rise to sterile 

 segments (leaves) alternately arranged and often densely crowded, 

 dendroidally and dichotomously dissected into 15-25 slightly flattened 

 segments 2-3 cm. long, subcostate ; older branches and at times the 

 ramuli, more or less muriculate ; numerous lateral terete secondary 

 branches arising in the axils of the leaves, longer below, shorter above ; 

 these bearing reduced leaves similar to those on the main fronds, pro- 

 ducing vesicles and the receptacles in their axils ; vesicles usually 

 solitary, smooth, spherical, 3.5-6 mm. diam., on the ends of pedicels 

 as long or longer than their diameter ; receptacles densely racemose, 

 substipitate, often with a vesicle or reduced leaf as a part of the group ; 

 the fruiting fronds often appearing nude as the leaves wear away ; con- 

 ceptacles conspicuous ; dioecious ; plants perennial. 



Grunow, Add. cog. Sargass., 1915, p. 338; Gardner, New Pac. 

 Coast Mar. Alg. II, 1918, p. 448. Sargassum piluliferum Farlow, 



